1. Field of The Invention
The present invention relates to a clip assembly for attaching a heat sink to a chip mounted on a printed circuit board, and particularly to a clip assembly for facilitating assembly of a heat sink to a chip.
2. Description of Prior Art
As chips such as microprocessors contain more circuitry and operate at faster speeds, greater amounts of heat are generated, which must be dissipated for reliable operation. A heat sink made from heat conductive material such as aluminum is commonly used to dissipate heat generated by a chip. The heat sink is retained in direct contact with the chip to dissipate the heat into the surrounding environment.
A heat sink is usually attached to a chip by a clip. A conventional clip 1 made from plastic is shown in FIG. 1. The clip 1 comprises a base 2, a pair of symmetrical arms 3 outwardly extending from the base 2 at an incline, and a pair of engaging posts 4 integrally extending from free ends of the arms 3. The base 2 abuts against a top surface of a heat sink 7 positioned over a chip 9 and retains the clip 1 on the heat sink 7. Each engaging post 4 has an expanded free end 5 for resiliently engaging with a corresponding engaging hole 80 defined in a printed circuit board (PCB) 8. A slot 6 is defined in the expanded free end 5 for providing additional resiliency. When the base 2 of the clip 1 is engaged with the heat sink 7, the arms 3 are pressed to engage the engaging posts 4 with the engaging holes 80 of the PCB 8. Since the engaging posts 4 are integral with the arms 3, proper alignment between the engaging posts 4 and the corresponding engaging holes 80 is difficult to insure. During engagement between each engaging post 4 and the corresponding engaging hole 80, the free end 5 of the engaging post 4 may be damaged due to an excessive interferential stress therebetween.
To solve the above-mentioned problem, resilient material, such as ABS, Nylon and Nylon 66, which are well-known in the art, is added to provide the clip 1 with additional resiliency. However, the retention force of the clip 1 is then insufficient to firmly retain the heat sink 7 on the chip 9 thereby adversely affecting the performance of the heat sink 7, especially when a fan (not shown) is attached to the heat sink 7 for enhancing cooling properties.
The present invention is directed at solving the aforesaid problems by providing a clip assembly consisting of a body and a pair of separate fasteners.